Numerical simulation on anti-freezing and temperature control of phasechange material in construction with loose-covering layer
During the construction of embankment and subgrade under negative temperature in winter,the com-paction performance of the materials will be reduced due to short-term freezing or freezing-thaw,which will lead to frost heave,thaw collapse,cracking and other diseases.The process of conventional covering insulation measure is complex,which makes it difficult to achieve continuous construction in negative temperature,and likely to ex-tend the construction period.Phase change materials(PCM)provide possibility to improve the frost resistance and ensure the construction time in winter.However,the high content of PCM affects the mechanical properties of soil.Therefore,the paper proposed a combined anti-freezing and temperature control measure of mixing PCM and loose-covering.Using the original upper loose-covering process in the construction,reduced the PCM content and the construction interference as much as possible,and solved the surface anti-freezing problem of the soil during the negative temperature construction exposure period.First,a finite element numerical model of construction phase change heat transfer considering the upper loose-covering was established,and the validity of the model was veri-fied.Then,the influence of different loose-covering thickness and PCM content on the temperature control effect of PCM in winter construction was quantitatively analyzed,and the estimation method of effective construction time of PCM was proposed.Finally,the suggestion of anti-freezing and temperature control measures was given.The 2％PCM content and 9.6 cm loose-covering thickness can meet the requirements of temperature control.This study provides a new technical way to solve the anti-freezing and temperature control problem during the construction in cold regions in winter.
phase change material-incorporated clay(PCM-clay)anti-freezing and temperature controlloose-coveringphase change heat transfernumerical simulation
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